1. Field of the Invention
This invention generally relates to a bicycle rim for use with a tubeless tire, a plurality of spokes and a hub adapted to be coupled to a bicycle frame. More specifically, the present invention relates bicycle rim, which maintains a tight seal with a tubeless tire even when tire deflection is caused by tire contact with an obstruction or protrusion.
2. Background Information
Bicycling is becoming an increasingly more popular form of recreation as well as a means of transportation. Moreover, bicycling has also become a very popular competitive sport for both amateurs and professionals. Whether the bicycle is used for recreation, transportation or competition, the bicycle industry is constantly improving the various components of the bicycle. One particular component of bicycles, which has been extensively redesigned over the past years, is the bicycle wheel. Bicycle wheels are constantly being redesigned to be lightweight and more aerodynamic in design as well as to be simple to manufacture and assemble.
There are many different types of bicycle wheels, which are currently available on the market. Most bicycle wheels have a hub portion, a plurality of spokes and an annular rim. The hub portion is attached to a part of the frame of the bicycle for relative rotation. The inner ends of the spokes are coupled to the hub and extend outwardly from the hub. The annular rim is coupled to the outer ends of the spokes and has an outer portion for supporting a pneumatic tire thereon. Typically, the spokes of the bicycle wheel are thin metal wire spokes. The ends of the hub are provided with a flange that is used to couple the spokes to the hub. In particular, holes are provided in the hub flanges. The wire spokes are usually bent on their inner end and provided with a flange that is formed in the shape of a nail head. The inner end is supported in one of the holes in one of the hub flanges. The outer ends of the spokes typically are provided with threads for engaging spoke nipples, which secure the outer ends of the wire spokes to the rim. In particular, the spoke nipples have flanges, which engage the interior surface of the rim. Alternatively, the spokes may be reversed, with the outer end having the nail head and the inner end having the threads for engaging spoke nipples, which secure the inner ends of the wire spokes to the hub.
With a spoke constructed in this manner, the nipples are installed in nipple holes formed in either the rim or the hub. The spokes are inserted through holes in either the hub flange or the rim with the flanges of the spokes engaging the areas surrounding the holes in either the hub flange or the rim. The male threads on the ends of the spokes are threaded into the female threads of the spoke nipples installed in the openings of the hub flange or the rim.
It is desirable in the bicycle industry to have as few spokes as possible. One problem with conventional spokes is the concentrated stress applied to the rim. Moreover, if fewer spokes are used, the stress on the rim becomes increasingly larger. Typically, conventional spokes are attached to either the inner edge or the lateral side portions of the rim. Thus, the amount of force that can be applied to the rim by the spokes depends mainly upon the thickness of the inner edge of the rim or the lateral side portions of a rim. In order to accommodate the stress from the spokes, the inner edge of the rim can be made thicker. However, making the rim thicker increases the weight of the rim.
In recent years, wheels have been designed with reinforcing members arranged on the outer ends of the spokes to aid in disbursing the stress concentrated on portions of the rim. Such a wheel is disclosed in Shimano""s U.S. Pat. No. 6,126,243. This wheel (i.e., rim, and spoke combination) is very strong, lightweight, and relatively simple and inexpensive to manufacture. However, this design requires drilling a plurality of access holes in the outer peripheral surface of the rim. The spokes and reinforcement members are inserted through these holes into spoke openings of the rim during assembly. These holes then have to be covered and a tubed tire installed. If a spoke needs to be replaced, the tire, tube and cover have to be removed from the rim so the spoke can be replaced.
Additionally, with these types of wheels, it is sometimes difficult to use a tubeless tire due to the plurality access holes. These holes are sealed in order for a tubeless tire to be utilized. The use of seals can allow leaking air, especially after prolonged use. Moreover, if a spoke needs to be replaced, the tire and seal have to be removed from the rim so the spoke can be replaced. Then, the seal and tire need to be replaced. This is inconvenient and can cause the seal and/or tire to be stretched or damaged.
There are some rims with tubeless tires on the market which do not include a plurality of access holes, eliminating the need for a seal. However, these prior rims for tubeless tires suffer from other deficiencies. Specifically, these rims can be expensive and complicated to manufacture and assemble. Moreover, these prior rims can cause punctures or leaks when an obstruction is contacted by the tire.
In view of the above, there exists a need for a bicycle rim which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
One object of the present invention is to provide a rim for a tubeless tire that minimizes loss of air when an obstruction pushes the tire axially toward the center plane of the rim.
Another object of the present invention is to provide a rim for a tubeless tire that has side mounted spokes disposed inwardly of the braking surfaces to avoid interference therebetween.
Another object of the present invention is to provide a rim for a tubeless tire that is relatively strong but relatively lightweight.
Still another object of the present invention is to provide a rim for a tubeless tire that is relatively simple and inexpensive to manufacture and/or assemble.
The foregoing objects can basically be attained by providing a bicycle rim comprising first and second annular side portions, an outer annular portion and a spoke attachment portion. The first and second annular side portions have first and second ribs to form opposing first and second annular tire supporting surfaces. The outer annular portion extends between the first and second annular side portions to form first and second outer corners. The outer annular portion includes first and second annular inclined surfaces with a curved connecting surface extending therebetween. The first and second annular inclined surfaces extend radially inwardly from the first and second outer corners to the curved connecting surface. The spoke attachment portion is rigidly coupled with the first and second annular side portions and the outer annular portion. The first and second annular inclined surfaces are angled between about three degrees and about seventeen degrees relative to an imaginary line passing through the first and second outer corners.
The foregoing objects can also basically be attained by providing a bicycle rim comprising first and second annular side portions, an outer annular portion and an inner annular portion. The first and second annular side portions have first and second ribs to form opposing first and second annular tire supporting surfaces. The outer annular portion extends between the first and second annular side portions to form first and second outer corners. The outer annular portion includes first and second annular inclined surfaces with a curved connecting surface extending therebetween. The inner annular portion extends radially inwardly of the first and second annular side portions and the outer annular portion to form an annular hollow area. The inner annular portion has a plurality of circumferentially arranged spoke openings. The outer annular portion has at least one aperture, but fewer than half of the number of spoke openings.
The foregoing objects can also basically be attained by providing a bicycle rim comprising first and second annular side portions, an outer annular portion and an inner annular portion. The first and second annular side portions have first and second outer ribs to form opposing first and second annular tire supporting surfaces and first and second inner bent sections. The outer annular portion extends between the first and second annular side portions to form first and second outer corners. The inner annular portion has first and second spoke attachment sections with radial lengths and an inner annular section extending between the first and second spoke attachment sections. The first and second spoke attachment sections extend radially inwardly from the first and second inner bent sections such that the first and second spoke attachment sections are offset from the first and second side portions. The first and second spoke attachment sections include a plurality of circumferentially arranged spoke openings having radial lengths larger than one half of the radial lengths of the first and second spoke attachment sections.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, disclose preferred embodiments of the present invention.